Logic Masters Deutschland e.V.

A tricky puzzle built around a unique global constraint. Enjoy!

For a smaller and more approachable taste of this ruleset: Between Neighbors (6x6)

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• Normal Sudoku Rules: Place the digits 1-9 in every Row, Column, and 3x3 Box
• Renban Lines: Digits on a purple Renban line are a set of consecutive digits (in any order)
• Thermometers: Digits along a gray thermometer strictly increase from the bulb to the tip
• Between Neighbors (Global Anti Min/Max): a digit may not be the minimum OR maximum of its orthogonally adjacent neighbors EXCEPT if the digit is a 1 or 9 (i.e. all digits other than 1 and 9 must have at least one lower neighbor and at least one higher neighbor)

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As an example, the 7 in this image satisfies the Between Neighbors constraint because it has a higher neighbor (8) and lower neighbors (134). The 6 is NOT valid because all of its neighbors are lower than 6 (2345).